What mode does the GPWS alert "WINDSHEAR, WINDSHEAR" refer to?

The GPWS alert "WINDSHEAR, WINDSHEAR" refers to a specific mode that is triggered by detecting wind shear conditions, which can pose significant hazards during takeoff and landing. This alert specifically relies on data from the aircraft’s airspeed and vertical speed, allowing it to detect changes in wind velocity over a very short distance, which can critically affect the aircraft's performance.

When the GPWS identifies that the aircraft is encountering severe and sudden changes in wind, it activates the "WINDSHEAR, WINDSHEAR" alert to notify pilots to take immediate corrective action. This is vital for safety, as wind shear can lead to loss of control if not addressed promptly.

The GPWS modes, each serving different functions and alerting mechanisms, help pilots understand the specific nature of the threat they might face. In this case, identifying "WINDSHEAR" alerts pilots to the risks associated with rapidly changing air currents, particularly during crucial phases of flight.